Japan

• Main Author: Akihiko Yatsu
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Oyashio; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.360.1704; http://www.pices.int/publications/scientific_reports/Report35/Sci_Rep_35_Japan_pp57_84.pdf

Seafood has always been a significant part of the Japanese diet and today accounts for about 40 % of the protein consumed by Japanese people. Domestic marine fisheries are generally divided into coastal fisheries, offshore fisheries, and distant-water fisheries (Table 9). From 1972 to 1988, Japan had the world’s largest fisheries. Catches increased through to 1984 with the maximum production of 12,820,000 t. The total catch of all marine species declined from the maximum in 1984 to 3,734,209 t in 2000 (Fig. 17). This was a change from 16.0 % of the world’s catch in 1984, to 5.1 % in 2000. In recent years, the fishery in China reportedly exceeds Japanese production. At present, Japan is the largest importer of fish products in the world. Approximately one third of the world catch in weight is exported, and Japan imports about 15 % in weight, or one quarter in value, of all exported fish products. The decline in catch in recent years (Fig. 17) is related to the natural decline in Japanese sardine abundance in the 1990s and the reduced catches in distant-water fisheries (Table 9, Fig. 18). Climate and Ocean Influences A major influence on the production of fish in the Japanese coastal and offshore fisheries is the structure and dynamics of the subarctic current, the Oyashio, the subtropical currents, the Kuroshio and Tsushima, and the transition area between the Oyashio and Kuroshio (Fig. 19). The changes in currents affect vertical mixing, which alters the supply of nutrients to the surface production zone, as well as migration and larvae transportation. Changes in nutrient supply affect primary production which, in turn, changes the abundance and species of zooplankton which are the principal food of fishes. Mechanistic linkages between climate and physical oceanographic changes and stock productivity generally occur through bottom-up scenarios. In the Oyashio area, the major feeding grounds of sardine, chub mackerel, saury, common squid, and many other species, zooplankton density since the 1970s has been ...